Dyeing by means of sulphuric esters of indanthrones



Patented Aug. 24, 1937 PATENT OFFICE DYEING BY S F SULPHURIC ESTEIiS OFINDANTHRONES David ,Alexander Whyte Fairweather, Falkirk, and 'John'Thomas, deceased, late of Polmont, Scotland, by Olive Morgan Thomas,Wilmslow,

and Barclays Bank Limited, Manchester, England, executors. assignors toImperial Chemical Industries Limited, a corporation of Great Britain aNo Drawing. Original application April 16, 1931,

Serial No. 530,724.

Divided and this application June 10, 1935, Serial No. 25,938.

, Great Britain April 16, 1930 I Claims.

This invention relates to improvements in dyeing by means of sulphuricesters of indanthrones, and it comprises methods of dyeing cotton, wooland other fibers and the like wherein the material to be dyed isimpregnated with triand di-esters of "an indanthrone compound, in theform of the azine and the color is then developed by removing thesulphuric ester groups by hydrolysis, advantageously by acid hydrolysisusing dilute solutions of mineral acids, the azine structure beingsimultaneously converted into a dihydroazine nucleus during theformation of the final shade or color. This invention is particularlydirected to dyeing processes wherein the said material is impregnatedwith an azine di-ester, such as anthraquinoneanthrahydroquinoneazinedisulphuric ester alkali metal salt, and the color developed by .meansof dilute mineral'acid, without the use of oxidizing agents. i

This application is a division of our copending application Ser. No.530,724, filed April 16', 1931,

' (U. S. Patent 2,019,530, November 5, 1935).

According to the present invention the di- 7 sulphuric leuco ester ofindanthrone in the azine form may be applied to the cloth and developedby a more simple procedure than heretofore required for the knownsulphuric acid esters of indanthrone. In preparing the dyebath we obtainhigher concentrations of potential coloring matter, calculated asindanthrone. We obtain increased actual solubility by the presence ofsulphuric ester groups and obtain a higher percentage of potentialcoloring matter due to the fact that the ester contains fewer of theseester groups. In developing the color on the material to be dyed, arelatively smaller amount oi salts of sulphuric acid are formed.

The greatest advantage of our processes is that development of color canbe obtained without the use of oxidizing agents or with a minimum ofsuch agents when their use becomes necessary. By using the sulphuricesters in the form of the azine, at least half of the necessaryoxidation is obtained by internal rearrangement of the structure of thedye. This rearrangement is explained more fully post. .This remarkableproperty of self-oxidation facilitates maintaining the amount ofoxidizing agent, below that which produces the said greening of thefinal shade, in those cases an automatic formation of the exact finalcoloring matter desired; the hydroxyl groups so produced, the presenceof which is indicative of undeveloped coloring matter, give rise tointernal rearrangements by which azine structures are converted into thedesired dihydroazine nucleus.

' The oxidizing action being within the compound itself, no arbitraryfixing of the oxidation is required. Greening of the final shade andundeveloped coloring matter are, so to speak, automaticallyavoided. Themajor precaution required is. to provide suflicient time and acid toeffect complete hydrolysis and leave substantially no sulphuric ester onthe material to be dyed. It a small amount 'of sulphuric ester does,remain, it can easily be removed by suitable washing because of itscomparatively greater solubility. r

The triand di-ester useful in our dyeing methods may be prepared byvarious processes.

In our copending application Serial No. 530,724, of which the presentapplication is in part a division and in part a continuation, there isdescribed the preparationof a large number of such, sulphuric esters.That application is d.i

\ rected to the methods of so making these esters and to thetrisulphuric esters formed as an intermediate product. The presentapplication is directed to the dyeing procedures using those esters.

While we find it advantageous to use the esters in the azine form,dihydroazines may be used. However, they should be converted into theazine form before the final development of color is effected.

The di-esters most advantageous in the pres in orange-red shades.

esters, the dyestufi may be to the mate ria in various ways. Paddingmethods, printing etc, may be employed.

dyebaths may be prepared by dissolv he di-ester in or aqueous solu- Gi.oinarily the di est employed in. the a really as the al netal salt,(sodium or, yam and the l. .e may be impreg of these dyeba-tlois orsolutions in anner. Then. the impregnated ma= 1 or without drying, isdeveloped by with dilute acid. Dilute solutions of ids, such assulphuric and hydrochloric y be used. No added oxidizing agent is rec uuen, the color being automatically developed by this acid treatment.

Printing pastes may be prepared with the azine- (ii-ester and, clothprinted in the usual manner. For instance, printing pastes may beprepared by mixing the azine di-ester with giycerine and gumtragacanthsolution in suitable proportions. The printed cloth maylikewise be developed with dilute solutions of mineral acids; no addedoxl dieing agent being necessary.

The following examples illustrate dyeing proc-- esses using the aminedi-EStQTISI terisl, treatr Eccemple 1 This example illustrates dyeingwith 3:3'-di= chloro anthraquinoneanthrahydroquinoneazine disulphuricester (prepared, for instance, by the process of Example 16 of U. S.Patent 2,019,530).

Cotton cloth is padded at about C. with concentrated solution of thesaid ester and then, with or without drying, passed through a 0.5 percent solution of hydrochloric acid.

A deep bright blue shade immediately de velops apparently correspondingto 3:3'-dichloroc0 indanthrone.

Example 2 This example illustrates a printing process using 3:3dichloro-anthraquinoneanthrahydroquinoneazine disulphuric ester. Theprinting paste is made up as follows:

Parts Diester 20 5O Glycerlnc 5 Gum tragacanth (5:100) 75 The paste isprinted on cotton or on woolen cloth, dried, aged for ten minutes,developed in 1% hydrochloric acid at C., and rinsed in soap.

Example 3 30 This example illustrates a dyeing method 11 s i n ganthraqulnoneanthrahydroqulnoneazine disulphurlc ester.

One part of the anthraquinoneanthrahydro: qulnoneazine disulphuric esteris dissolved in 100 parts of water, the temperature is raised to about60 C. and 10 parts of cotton yarn entered and kept at about 60 C. forhalf an hour, salt being added to assist exhaustion. The yarn is dyedThe yarn is removed and immersed in a. bath containing 1 per centhydrochloric acid at 50 or 60 C. for a few minutes, the said red-orangeshades being converted by this acid treatment to blue.

15 The following examples illustrate dyeing proco I, es accrues Example4 it This example illustrates dyeing proc using ananthraquinoneanthrahydroqinnonee disulphuric ester containing nuclearhydro. groups obtainable as described ante. 15

Two parts of a 10 per cent paste of the azine cli-ester are dissolved in200 parts of it" and 10 parts of cotton cloth is entered at and workedat that temperature for 30 mi .0 parts of sodium chloride are then adthe dyebath and the dyeing continued for M1,, ther 30 minutes.

The cotton is thus colored a reddish hi which is changed to a brightblue by imrn in a l per cent solution of sulphuric acid at l The blueshade is not so red as the shade oi" anthraquinone dihydroazine and thebody he a clianthraquinone dihydroazine derive. This appears torepresent a simpler metho obtaining a dyeing of a dianthraquinone dibazine derivative than any previously desci whether by the vat or solubleester methods.

Example 5 This example illustrates another method (a? dyeing with thedyestuif used in Example l.

10 parts of woolen cloth well wetted out 2 c entered into the dyebath asused in Example and the temperature raised to to Exhaustion is efiectedby the cautious addition of dilute acetic acid.

The dyeing which already is somewhat blue in color towards the end ofthe process, is immers for 5 minutes in a 1 per cent solution of sulplacid at 15 0., when a bright blue shade is veloped.

In the foregoing illustrative examples of ing methods, it is to be notedthat the develop ment of color is effected by treatmentwith dilutemineral acids; no oxidizing agent being required. This-is a feature ofsuch processes and an advantage of our new azine di-esters. These newazine di-esters are, so to speak, self-oxidizing, that is, when the twoester groups are removed or. by hydrolysis with the dilute mineral acid,the hydroxyl groups so formed are oxidized by in ternal rearrangementinvolving conversion 01' the azlne ring into a dihydroazine structure.

The di-esters of an anthraquinoneanthrahy- 00 droquinoneazine may beprepared from the tetra sulphuric esters of a dianthrahydroquinoneazine,by the two-step method described in our copencb ing application SerialNo. 530,724, wherein one sulphuric ester group is first removed from the65 tetra-ester by a restricted acid hydrolysis or by hydrolysis in anaqueous medium in the presence of a reducing agent, and then a secondsulphuric ester group removed by hydrolysis in an aqueous medium in thepresence of an oxidizing agent. 70 The details of such processes, asapplied to the tetrasulphuric ester of 3:3'-dichloro-dianthrahydroquinoneazine and of dianthrahydroquinoneazine are set forth in theaforesaid copending application. 75

1 OSOaNa Such azine di-esters, per se, are new. Theanthraquinoneanthrahydroquinoneazine 5 disulphuric ester is believed tohave, in the form of the sodium salt the following formula:

' 40 OSOaNa It is a bright red body having good solubility in water. Itssolution in water is not colored violet by the addition of causticalkali. On reduction with sulphide and hydrosulphite and alkali, thecolor of the solution changes to blue green.

the vat dyestuff indanthrone is precipitated.

The 3 3 -dichloro-anthraquinoneanthrahydroquinoneazine disulphuric esteris believed to have,

in the form of the sodium salt, the following formula: I

It is likewise a red soluble ester. Its properties are similar to thoseof anthraquinoneanthrahydroquinoneazine disulphuric ester; dichloro-in-70 danthrone being precipitated on treatment with dilute mineral acid} IThe development of an indanthrone coloring matter from the azinedi-ester upon treatment with dilute mineral acid, is shown diagrammati-75 cally as follows; anthraquinoneanthrahydroquion treatment with dilutemineral acid noneazine disulphuric ester being used for purposes ofillustration:

self-oxidation From the foregoing showing it is clear that the dilutemineral acid efiects removal of the two sulphuric ester groups formingtwo hydroxyl groups. Then migration of the hydrogen of those hydroxylgroups to the azine ring, effects conversion of the azine intodihydroazine with simultaneous oxidation of the said hydroxyl groups.This is what is here called self-oxidation; oxidation by internalrearrangement. Thus the development of the desired coloring matter isautomatically obtained; the desired dihydroazine form and oxidation ofhydroxyls being produced upon hydrolysis.

This internal rearrangement is characteristic of these azine dl-estersas a class.

While an essential feature of our new dyeingprocesses is thisself-oxidation, and the use of such'azine di-esters, it is not mandatoryto use the azine di-ester as a starting material or dyestuff. Ourprocesses may be practiced using other n ester produced in situ, beforedevelopment of the final color, by a suitable treatment. The azinedi-ester may be formed in situ, to advantage, by subjecting the clothimpregnated with a di-ester to treatment with an alkaline solution of anoxidizing agent; this treatment being controlled remove one sulphuricester group and form an azine compound. The so treated cloth may befurther treated to eliminate any excess of oxidizing agent before finaldevelopment of color with acid. Sodium sulphite may be used to destroyexcess of hypochlorite when that substance is used as the oxidizingagent.

Again, the dyebath may be prepared by dissolving a tri-ester inanalkaline aqueous solution or water and then forming the azine diesterin situ before cloth or yarn is entered into the bath; the azinedi-ester being advantageously formed in situ by adding a suitable amountof oxidizing agent or alkaline solution thereof to Sil cation of themodifications mentioned ante, to

dyeing processes:

Example 6 This example illustrates a dyeing method wherein an azinetri-ester is applied to the cloth and the azine di-ester is produced insitu upon the cloth prior to development to the final color.

0.2 part of dianthrahydroquinoneazine trisulphuric ester are dissolvedin 200 parts of water together with 10 parts of sodium chlofide and 10parts of cotton cloth entered at 50 C. and worked for 30 minutes. Thedyeing which has a reddish orange shade is squeezed and immersed in abath containing 1 per cent of sodium hypochlorite, 2 per cent of causticsoda and 10 per cent of sodium chloride for one minute at 50 C. Theshade changes toward the red, and the cloth is now squeezed and runthrough a 2 per cent loath of sodium-sulphite being finally developed ina l per cent sulphuric acid bath at 60 C. when a blue shade is produced.

In this example treatment of the cloth im pregnated with the tri-ester,with the solution of sodium hypochlorite, forms theanthraqulnoneanthrahydroquinoneazine disulphuric ester in situ on thecloth. The treatment with sodium sulphite is to eliminate any excess ofthe oxidizing agent. The treatment with dilute sulphuric acid, asspecified, forms thefinal coloring matter by hydrolysis and internalrearrangement, of the dyestuif.-

In Example 6, other azine tri-esters might be used, for instance,3:3'-dichloro-dianthrahydroquinoneazine trisulphuric ester. Likewisedilute solutions of other mineral acids, for instance, hydrochloricacid, might be used to develop the final color. Further, the othersuitable oxidizing agents might be used in lieu of the sodiumhypochlorite to form the azine di-ester in situ.

This method of developing the azine di-ester 70 in situ on the clothfrom a tetraester, is not limited to using azine tri-esters. It may bealso practiced with other tri-esters, for instance,anthranolanthrahydroquinone dihydroazine trisulphuric ester. Thefollowing example illustrates the use of such an anthranol compound.

Example 7 In this example the tri-ester of anthranolanthrahydroquinonedihydroazine is used. This tri-ester is somewhat difierent from thetri-ester used in Example 6 and it may be represented in. the form ofsodium salt by the following formula:

NaOaSCl) T l l NH H OSOKNB HN I I O SOalNfl 0.2 part of theanthranolanthrahydroquinone dihydroazine trisulphuric ester, aredissolved in 200 parts of water together with 10 parts of sodiumchloride, and 10 parts of cotton cloth entered at 50 C. and worked for30 minutes.

The deep orange-red dyeing is squeezed and immersed in a bath containing1 per cent of sodium hypochlorite, 2 per cent of caustic soda and 10 percent of sodium chloride for 1 minute at 50 C. The shade changes towardsbrown, and the cloth is now squeezed and run through a 2 per cent bathof sodium sulphite, being finally developed in a 1 per cent sulphuricacid bath at 60 C. when a blue shade is produced.

In this example, the treatment with alkaline hypochlorite solution notonly converts the dihydroazine into an azine compound, but also oxidizesthe anthranol structure into an anth aquinone nucleus simultaneous withthe removal of one sulphuric ester group, thus producinganthraquinoneanthrahydroquinoneazine disulphuric ester in situ. Thisprocedure may be used with any of the tri-sulphuric esters obtainablefrom the tetrasulphuric ester by a stronger reduction treatment than isnecessary to form the triesters of dianthrahyclroquinoneazine.

The following example illustrates the formation of azine disulphuricester from a trisulphuric ester in situ in the dyebath before thedyestuff is applied to the material to be dyed.

Example 8 200 parts of a 10 per cent paste (calculated as indanthrone)of dianthrahydroqujnoneazine trisulphuric ester, together with 400 partsof water and 50 parts of 20 per cent caustic solution are warmed to 50C. When the tetrasulphuric ester has dissolved, 12.5 parts of potassiumpersulphate are gradually added. When the addition is complete thetemperature is raised to "70 C. for half an hour. If necessary, sodiumsulphite may then be added to eliminate any excess persulphate ifpresent. The liquor so obtained may be filtered if desired.

This solution is an advantageous dyebath for use in our dyeingprocesses. It may be used according to the dyeing processes of Examples3 and 4; the red solution obtained in this example, being used in lieuof the solutions of anthraqulnoneanthrahydroquinoneazine disulphuricester disclosed in the said examples. The procedures to be followed aresubstantially the same; the final color being developed by dilutesolution of mineral acid.

' ordinary use.

$0 This example illustrates dyeing woolen cloth Of course other azinedi-esters might be formed in situ in the dyebath prior to applying thedyestuff to the cloth, yarn, etc., from other tri-esters.

Although in our processes it is advantageous to form the azine di-esterbefore the impregnated material is treated with mineral acid to developthe final color, our processes may be practiced using the tri -sulphuricesters and simultaneously forming the azine disulphuric ester anddeveloping the final colorwith mineral acid. In' this modification ofour processes, the tri-ester is applied to the material to be dyed andthen the impregnated material is treated in a developing bath comprisinga dilute solution of acid containing an oxidizing agent dissolvedtherein. Such developing baths may be prepared by dissolving coppersulphate and like oxidizing agents in dilute solutions of mineral acid,such as sulphuric and hydrochloric acids. About 1 per cent mineral acidand approximately 2 per cent copper sulphate give baths of suitableconcentration for The amount of oxidizing agent used should be merelysufiicient to oxidize one pair of hydroxyl groups (formed by acidhydrolysis) to the desired quinone oxygens; the other pair of hydroxyls(so formed) being oxidized by internal rearrangement with the formationof the dihydroazine compound, In this way over oxidation can be easilyavoided.

The following examples illustrate such processes using the azinetrisulphuric esters.

Example 9 In this example cotton yarn in the form of hanks are dyed withindanthrone coloring matter derived from dianthrahydroquinoneazinetetrasulphuric ester.

20.5 parts of a. solution of dianthrahydroquinoneazine trisulphuricester, containing the equivalent of l per cent indanthrone, are made upto 410 parts with water and heated to C. 20.5 parts of cotton hanks arewetted out and immersed in the bath so prepared, and after working forhalf hour 30.5 parts of common salt are added. After a final half hoursworking the hanks are lifted, wrung andimmersed for about 5 minutes in asolution of l per cent copper sulphate crystals, 1 per cent-ofconcentrated hydrochloric acid at 85-90 C. This causes the reddish colorto pass through purple'to bright blue. The hanks are removed, washed,soaped, washed and finished. The material, if desired, may be padded ina normal way in a somewhat stronger bath of any strength, and aftersqueezing and drying is steamed and developed.

Example 10 NaOiSO minutes at this temperature.

using dianthrahydroquinoneazine trisulphuric ester as the dyestufl.

One part ofdianthrahydroquinoneazine triester is dissolved in 200 partsof water at 50 C. and the temperature raised to C. 5 parts of woolencloth, which has been scoured for 5 minutes in 1 per cent ammoniasolution at 95- C.,

are then entered. The cloth is worked for 15 minutes during which timethe temperature is raised to the boil and dyeing is continued for 10 5parts of common salt are added at intervals during a further 20 minutes,the cloth being worked during this period. The material is then raisedand squeezed before developing in the following solution for threeminutes at 100 C.:

Per cent Copper sulnhatp v 2 Hydrochloric acid 1 The dyeing is washed inwater, soaped for 5 minutes at 60 C. in 1 per cent soap solution, washedand dried.

. Parts Dianthrahydroquinoneazine 'trisulphuric ester 20 Glycerine 5 Gumtragacanth (5:10(l).

The paste is printed on cotton or on woolen cloth, dried, aged for 10minutes and developed in 1 per cent hydrochloric acid and 2 per centcopper sulphate solution at 0., rinsed and soaped.

The tri-esters used in the foregoing examples may be prepared fromthetetrasulphuric esters by treating said tetra-esters with reducing agentsin an aqueous medium. Generically such processes comprise the controlledremoval of a single sulphuric ester group, the treatment being stoppedat that point. Such processes are described in detail in our copendingapplication Serial No. 530,724.

Preferably the trisulphuric esters are prepared in the form of the azinecompound for use in these dyeing processes. Such tri-esters may berepresented using dianthrahydroquinoneazine trisulphuric ester as anillustration, by the following isomeric formulae:

no i i t Zsoim Naoaso osoma osotNa osoma conversion of thesetrisulphuric esters may "'ainniatically represented as follows, using .etil-ester as an illustration:

NUZSOaNB l osoaNs O H o i t 0 on C I (BE c t 0 EN II in all ourprocesses, we believe that two or more of the above changes orconversions are involved. In our processes'vvhereln a trisul ihuricester is applied to the cloth or other materials.

rapid succession; the rapidity of action being so great that thesecomplex changes appear to be a single change. However, We believe aseven in that case, there is the conversion ofanthraquinoneanthrahydroquinoneazine into d'anthrahydroazine. That suchis a fact, is evid need by the development of the final color with. anamount of oxidizing agent only half of that required to theoreticallyconvert the four hydroxyls oi diarithrahydroquinoneazine into quinoneoiiygens. fins We believe that in all of our recesses at least half ofthe required oxidation is a self oxidation involving internalrearrangement T .iin the dyestuffs; a diliydroazine being the product.

In the foregoing examples, the parts parts by weight. Those examples,nierel i trate our invention and in no way to considered limiting thescope of this inventi While We have specifically mentioned metal saltsof these sulphuric esters, on gliUC- esses are not limited to suchsalts. Any suitable salt of these esters may he used. G our invention isapplicable to these trisnlphuric esters a class.

What we claim is:--

i. In the process for dyeing fibers throne dyestuffs, the improvementprises impregnating the fiber with solution of a disulphuric leuco ester0 color in the fiber hy treating the s dilute solution oi acid, in theabsence oxidizing agent.

2. The process of claim 1 wherein th nhuric acid ester with which thefiber nated is the leuco dmlphin'lc ester oiuinoneanthrahydroquinoneazine.

3. The process of claim 1 wherein t e azine disulphuric ester is formedin Sl't j. on. material to he dyed.

4. As an improved process of dyeing nii. danthrone dyes, the processwhich compri es applying to the fiber to he dyed an aqueous som tion ofa disulphuric ester of a leuco indanthrone in the azine form andsubsequently cor the fiber impregnated with said azine cu or, with adilute solution of mineral acid, in. the absence of an oxidizing agent.

5. The improved process of claim 4 wherein a solving ananthraquinoneanthrahydroqulnoneazinedisulphuric leuco ester in anaqueous solution, impregnating the material to he dyed with saidsolution, and subsequently immersing the impregnated material in adilute solution of a mineral acid, in the absence of an oxidizing agent.

7. The process of claim 6 wherein said M ral acid is hydrochloric acid.

8. The process of claim 6 wherein said mineral 10. The process of claim9 wherein said oxidizacid is sulphuric acid. ing agent is an alkalinehypochlorite solution.

9. As an improved process of dyeing with indanthrone dyes, the processwhich comprises im- DAVID ALEXANDER WHYTE pregnating a textile materialwith an aqueous FAIRWEATHER. 5 solution of a trisulphuric leuco ester ofa reduced OLIVE MORGAN THOMAS, indanthrone, treating the impregnatedtextile BARCLAYS BANK, LTD., 1 material with an oxidizing agent to forman Manchester Trustee Dept, azine di-ester in situ, and subsequentlydevelop- By THOMAS ERIC SONE, ing the final color by contacting theso-treated Manager. 10

v textile material with a dilute solution of mineral Emecutors of theEstate of John Thomas, De-

acid. ceased.

